6
Using the Board
It is easy to prepare the evaluation board for use. You just need to solder cables for DC supplies, have proper cables for
HVDC+/HVDC- high voltage bus, and load connections. The evaluation board has a default connection as shown in
Table 1 when it is shipped to the customer. We offer several power supply schemes from which you can choose.
Power Supply Schemes
The evaluation board is built with DC supply flexibility in mind; choose a power supply scheme from the seven available.
Table 1 shows all the possible power supply schemes that work for the evaluation board. A description of each scheme
is given; you are encouraged to explore each scheme and decide which one works best for your needs:
1. Scheme 1 is the simplest and possibly the cheapest scheme. A +5 V isolated DC supply is supplied externally to
power the low voltage V
cc1
circuit. Another external supply (+12 V~20 V for V
cc2a
) is needed for the gate driver driving
the power MOSFET at the bottom inverter arm. V
cc2b
supply is obtained from V
cc2a
by bootstrapping. For this to
work, the bootstrap components D3b and R6 must be connected, all S2 jumpers must be shorted so that no negative
supply of V
ee
is allowed, and the Signal Input 2 is at 180
°
out of phase to Signal Input 1. All S2 jumpers are shorted to
connect V
ee
to V
e
so that there are no negative supplies. S3 jumpers are shorted by default but this has no effect on
actual operation of the board. Contact Avago Technologies if bootstrapping operation works are required.
2. Scheme 2 is similar to Scheme 1: it has V
cc1
and V
cc2a
supplies. However, as the power MOSFET used gets bigger,
so does the driving power. Because a bootstrapped power supply can only handle a lower driving power, it is not
suitable for use when Qg of power MOSFET rises above 200 nanocoulombs (nC). A third external supply (+12 V~ 20
V for V
cc2b
) will be needed.
3. Scheme 3 is similar to Scheme 2 in that it uses three external supplies at V
cc1
, V
cc2a
and V
cc2b
. Scheme 3, however, has
the advantage of getting negative supplies for V
ee
(or V
eea
and V
eeb
) by introducing a 12 V Zener diode at D4 and R7
of around 1 k
Ω
to provide proper biasing current at D4. For this scheme to work, both the S2 and S3 jumpers must be
open while the external supplies (+15 V ~ 24 V) on the high voltage driver side are to be connected across V
cc2
and V
ee
pins only, not the V
e
pin. As the external supply changes from +15 V to +24 V, V
cc2
will stay at +12V, but V
ee
changes
from -3 V to -12 V, all w.r.t. virtual ground at V
e
.
4. Scheme 4 is another simple scheme; an alternative to Scheme 1. Here, only one external supply for V
cc1
is needed.
V
cc2a
is obtained by a lower power DC/DC converter at IC2a, with V
cc1
as V
in
and +12 V output at V
cc2a
w.r.t. V
ea
. V
cc2b
supply is obtained from V
cc2a
by bootstrapping. For this to work, the bootstrap components D3b and R6 must be
connected, all S2 jumpers must be shorted so that no negative supply of V
ee
is allowed, and the Signal Input 2 should
be 180
°
out of phase to Signal input 1. S2 is shorted to connect V
ee
to V
e
so that there is no negative supply. S3
jumpers are shorted by default but this has no effect on actual operation of the board.
5. Scheme 5 is similar to Scheme 4: it has V
cc1
and a DC/DC converter for V
cc2a
. However, as the power MOSFET used
gets bigger, so does the driving power. Because a bootstrapped power supply can only handle a lower driving power,
it is not suitable for use when Qg of power MOSFET rises above 200 nanocoulombs (nC). A second DC/DC converter at
IC2b with V
cc1
as V
in
and +12 V output at V
cc2b
w.r.t .V
eb
. All S2 jumpers are shorted to connect V
ee
to V
e
so that there
are no negative supplies. S3 jumpers are shorted by default but this has no effect on actual operation of the board.
6. Scheme 6 is similar to Scheme 5 with the use of V
cc1
and two DC/DC converters. Each DC/DC converter, however, has
dual outputs set at ±12 V to allow for the availability of negative V
ee
(at V
eea
and V
eeb
). Therefore, all S2 jumpers must
be open, while all S3 jumpers must be shorted.
7. Use Scheme 7 if dual-output ±12 V DC/DC converters are not available or dual-output ±9 V DC/DC converters are
preferred. 12 V V
cc2
can still be obtained using ±9 V DC/DC converters by introducing a 12V Zener diode at D4 and R7
of around 1k
Ω
to provide proper biasing current at D4. For this scheme to work, both the S2 and S3 jumpers must be
open. As the total voltage across V
cc2
w.r.t. V
ee
stays at 18V (=9V+9V), V
cc2
of 12 V will be obtained through the 12 V
D4 Zener diode, and -6V at V
ee
, all w.r.t. virtual ground at V
e
.
